Method for preparing detergent compositions



July 2l, 1959 J. A. MlLENKr-:vlcH l-:T AL 2,895,916

` METHOD FOR PREPARING DETERGENT coMPosITroNs Filed May 15, 1956 wwwa,

Jar/26.5 tgig/'IMQ BY com. (2,9 @mda 1- www.,

ATroRNEYs METHOD FOR PRfEPARlNG 'DETERGENT COMPOSITIONS Joseph A.Milenkevich and James Henium, Cincinnati, 1Ohio, assignors to TheProcter & Gamble Company, Cincinnati, Ohio, a corporation of `OhioApplication May 15, 1956, Serial No. 585,017

8 Claims. (Cl. 252 99) This invention relates toA a method for preparingdeter-gent compositions.

More expressly, this invention relates to a method for preparingdetergent compositions which are particularly useful in automaticdishwashing machines.

Detergent compositions comprising in combination an alkaline detergentsalt (eg. sodium metasilicate), an alkaline condensed phosphate (e.g.sodium tripolyphosphate), and chlorinated trisodium phosphate have beensuggested as having particular utility for dishwashing applications(U.S. Letters Patent 2,689,225). The formulation of such compositions,which are made up of agglomerates of the various ingredients, hasheretofore been accomplished through the addition of aqueous silicate toa mechanical mixture of alkaline condensed phosphate and chlorinatedtrisodium phosphate.

It has now been observed that a composition prepared in this manner andpacked in cardboard cartons is characterized by a tendency to cakeduring normal storage and to form a gum or gel in use. This lattercharacteristic isparticularly evident when such a composition is used ina dishwashing machine which has two wash cycles, i.e., two distinctintervals of operating time with a detergent present in the water.Machines of this type normally contain. two cups for holding a detergentcomposition, each of which automatically releases the detergent into themachine near the beginning of the successive wash cycles. With detergentcompositions preparedaspointed out above, the detergent present in thecup adjusted to releasenear the beginning of the second wash` cycleusually becomes gummy and does not completely dischargefrom thedetergent cupa condition which is objectionable for several apparentreasons.-

4It is an object of this invention to Vprovide a means `for preparing`detergent compositions suitable for dishwashing applications whichV areessentially free of the aforementioned undesirable characteristics.Other objects and advantages will be apparent from the followingdetailed description and accompanying drawing, which -is a comparison ofthe rate of hydration of'sodium t-ripolyphosphate in a particulardetergent composition. when that composition is prepared in accordancewith the process of the present invention and when the composition isprepared by prior methods;

Althoughwe do not wish to be bound by any theoreti- `V`calconsiderations, vit is our belief that the undesirable United sansPaf-em o w 2,895,916 Patented July 21, 1959 ice thus gives rise to theabove mentioned defects in the product.

We have now found a method whereby detergent compositions may beprepared which exhibit none of the `aforementioned undesirablecharacteristics although such compositions comprise the constituents setforth hereinphates of the calcium and magnesium ion sequesteringcharacteristics ofthe aforementioned compositions preinhibitsrapidhydration of the condensed phosphateand type whose Na2O/P2O5 ratiosrange from lvl to 1.67:1`. The term alkali metal silicate indicatesthose silicates having an average Si02/ alkali metal oxide ratio ofabout 2.0 to 3.4 and includes mixtures of silicates having dissimilarSiO2/ alkali metal `oxide ratios. The term chlorinated trisodiumphosphate is used to designate a composition consisting of trisodiumphosphate and sodium hypochlorite in intimate association in acrystalline form. The chlorinated trisodium phosphate may contain from1% to 5% available chlorine and may be prepared by the methods of U.S.Letters Patent 1,555,474 or 1,965,- 304, or modifications thereof.

rPhe essence of our invention lies in the particular rsequence in whichthe various constituents of the detergent compositions are admixed. Wehave found that in order to obtain a composition comprising theaforementioned constituents which is characterized by resistance tocaking on storage and formation of dicultly soluble gels in use, theparticular sequence of steps herein described must be closely adheredto.

By way of illustration, a dishwashing composition comprising, by weight,45 parts sodium tripolyphosphate, 32 parts of a 41% aqueous solution ofsodium silicate having an average SiO2/Na20 ratio of about 2.9, and 20parts chlorinated trisodium phosphate was prepared in accordance withthe process of our invention in the following manner:

The sodium tripolyphosphate, in a substantially anhydrous condition, andat room temperature, was placed Iin a ribbon mixer wherein the sodiumsilicate in the form of a 41% aqueous solution, heated to a temperatureof about 1GO-120 F. to control viscosity, was sprayed onto the phosphatewhile it was being agitated. The addition of the aqueous silicate causedhydration of the `tripolyphosphate to `take place with the evolution ofheat. Consequently, in `order to maintain the phosphate-silicate mixturein a non-liquid condition, precautions were taken to prevent thetemperature of the mix from rising above about F. (Abovethistemperature, this mixture losses its discrete particlecharacteristicrand becomes pasty.) Following the addition of the entireamount `of silicate solution, the chlorinated trisodium phosphate wasadded and the entire mixture was then cooled to room temperature withcontinuous agitation. The resultant mixture was then allowed to age forabout four hours. During this aging period, while hydration of thetripolyphosphate was proceeding to substantial completion, the mixturewas intermittently stirred to prevent solidiication into a hard mass.After completion of the aging period, the agglomerates resulting fromthe foregoing process were reduced to the desired sizerfor subsequentpackaging.

In connection with the theoretical considerations hereinbeforeexpressed, a comparison was made of the rate of hydration of thealkaline condensedphosphate in detertionand the second was prepared byrst mechanicallyV mixing the 4sodium tripolyphosphate and thechlorinated ytrisodium phosphate and then. spraying the aqueous sili,cate solution onto this mixture.

The rate'of hydration of the sodium tripolyphosphate in each Vof thesemixtures,

as j depicted bythe curves ofthe drawing, was based upon the amount ofthe hexahydrate' of this phosphate present in the composition aftercertain periods of time as 'deter-V rnined by X-ray diffractionmeasurements.`

Itis apparent vfrom the drawing that the sodium tripoly# r phosphate inthe detergent composition prepared in ac-v cordance with thefpres'ent'process hydrates at a much more'rapid rate Ythan'it does in thedetergent'compo'sition 'prepared according' to prior methods.

Although our process has been described herein as a batch operation, itis to bev appreciated that it can also beV readily carried out as asemi-continuous or continuous operation. Moreover, phosphates other thantripolyphosphate, for example, tretrasodium pyrophosphate and Ythehigher phosphates, can berused to advantage. It is also to beappreciated that other silicates can be used, the average SiO2/ alkalimetal oxide ratio of such silicates as we have found suitable being inthe range from about 2.0 to about 3.4 and more preferably in the rangefrom about 2.7 to about 2.9.V y I These silicates can be added inlourprocess in a number of diiferentways. They can be in drypowder form-',this would call for the independent addition of water to hydrate thealkaline condensed phosphate-or they can be in aqueous solution-servingas the carrier for at least a portion of the water required for thedesired hydration the phosphate. Alternatively, a portion of thesilicate, normally in the form of an aqueous solution, can be added tothe alkaline condensed phosphate prior to addition of the chlorinatedphosphate with the remaining amount of silicate being added after thechlorinated phosphate addition. We have found that when observingV theprecautions relative to moisture additionj as pointed out hereinafter,at least about 50% of the water which is to be added, whether such wateris added independently or,

in combination in an aqueous silicate solution, should be added prior toaddition of the chlorinated trisodium lphosphate if the benelits 'of ourinventionV are to Vbe realized. In any fevent, the addition of thealkali-metal silicate prior to the chlorinated trisodium phosphateaddition appears to promote the desired agglomeration of -the productconstituents. i Y Y 'Regardless of whether the water is added`independently, as whenV the silicate is in the form of a dry powder,

Yor in combinaiton -iri an aqueous silicate solution, the addition ofamounts of Water from about 12% to about 25% by weight of the nishedproduct (exclusive of that water introduced with the chlorinatedtrisodium phosphate) find ready application in ourV process. However,the amount of water must be at least adequate in all cases to wet thecondensed phosphate sufficiently to in- Iduce agglomeration of theconstituents. VNormally, the total amountof water which We prefer toadd, either independently or in combinaton in an aqueous silicatesolution, is sufficient to theoretically completely hydrate'thecondensed phosphate. The total amount ofwater added, however, shouldvnot be in excess of that amount which will allow the condensedphosphate-silicate mixture to -maintain'its discrete particlecharacteristic.

l.; If desired, a non-ionic detergent, such as the Pluronics-(condensates.of.ethy1ene oxidewith afhydrophobic base i of a non-ionicdetergent agent( Also, we have found that some additional benefits Yinformed by condensing propylene oxide with propylene glycol-marketed byWyandotte Chemicals Corp.) or the Hyonics (e.g. fattyalkylolamides-'marketed by Nopco Chemical Co.) can be used inconjunction with the aforementioned constituents in a detergentcomposition. A1- though in our process the YpointY of addition of suchnonionic detergent, normally in the form of an aqueoussolution,"is`,`not critical, 'we have found 'indications that it aids inpromoting agglomerationof the constituents and promotes, in general,further. improvements in the caking and gummiug "or`ge1lingcharacteristics of theproduct.

Detergent compositions which can be advantageously prepared our processcomprise in combination from about% to about 60% alkaline condensedphosphate, from about 8% to about 20% alkali metal silicate as silicatesolids, and from about 15% Vto about 30% of chlorinated trisodiumphosphate with or without the addition product caking and gumming .orAgelling characteristics can'be'obtained by adding other ingredients tothe deter,-V

gent composition prepared in accordance with our process. Additiveswhichwe have found to be particularly advantageous Vfor these purposesVinclude such endothermic,

rapidly dissolving salts as urea and potassium nitrate, hyi drated saltssuch'as hydrated ortho, pyro, and tripolyphosphate, and inertdiluentssuch assilica andtalc.

-In the, following examples,which are merely illustrative, Yourinvention being limited only by the scope of the appended claims; all parts are byv weight.

Example I f; poured, atroom temperature, over the phosphates, while theywere being agitated, during aperiod of about 3 minutes." During .thissilicate addition, agglomerates ranging Vfrom the size ofY grains ofsand to marbles formed, while the temperature of the mixture rose from82 to 95 F.

These `agglomeratesrwere then aged in the mixer for about 15V minuteswith periodicv agitation every two to three minutes. The temperature ofthe agglomerates rose to 113 l1:",during this aging period.

' The agglomerates were granulated in la low-speed hammer mill to pass a10-mesh Tyler screen, and this product was immediately packed intocardboard cartons. "After two hours, the pouring characteristics of theproduct were noted. The product was then repacked in cardboard cartons,allowed to stand at room temperature for 24 hours, and 4the'po'uringcharacteristics were again -noted." n n A second detergent compositionwas prepared in ac- Vcordance' with the above procedure except that thesil- Yicate solution was Yadded'prior to theaddition of the chlorinatedtrisodium phosphate. During the silicate addition, the temperature inthe mixer rose from 84 to 114"` F. and then dropped to 108 F. after a15-minute aging period. 'Ihe pouring characteristics of the product wereobserved in the Ysame manner as above described.

It was observed from these pouring tests that the addition of' thesilicate solution p rior to the addition of chlorinated trisodiumphosphate resulted in a product having markedly/superiorcharacteristics, especially with regard to resistance to caking'. 7

It has been pointed out hereinbefore that detergent compositionscomprising an Valkaline condensed phosphate, anY alkali-metal silicate,and chlorinated trisodium phosphate, when prepared by adding aqueoussilicate `to a mechanical mixture ofthe the phosphates, tend to -form agum or gel in use and that Vthis characteristic is particularly evidentwhen'such composition is used in a dishwashing machine having two -washcycles.V vIn the followingexamples, a comparison is made of the gummingand/ or gelling tendencies of detergent compositions prepared by theabove method and by the method of our invention. Since thischaracteristic can ybe appropriately evaluated through practical use inan automatic dishwasher utilizing twowarsh cycles, the data appearing inthe subsequent examples were obtained through this medium.

The particular dishwashing machine used for the evaluations had twoseparate detergent cups, each having aV capacity of. about 20 cc., whichwere filled with the productto be tested. The machine cycle was asfollows: First wash, second wash; first rinse; second rinse. During thefirst wash cycle, the detergent in one of the cups was washed out by thewater action in the machine and was utilized in this Wash cycle. Duringthis time, the detergent in the second cup was protected against Washingout but did come into contact with steam and sprayA during the firstwash cycle. At the beginning of the second wash cycle, `the detergent inthe second cup was made available to the water action in the machine andwas washed out of the cup and utilized in this second Wash. Thedegree ofgumming and/ or gelling Was determined by observing the proportionateamount of detergent retained by lthe second cup after each of the secondwash, rst rinse, and second rinse cycles.

Example 2 The detergent compositions prepared in accordance with -theprocesses outlined in Example 1 after aging for two hours were used in adishwasher of the type described above; The figuresk appearing in thetable below Krepresent the proportionate amount of detergent retained inthe second detergent cup after completion of It may be readily seen fromthe above data that the process of our invention results in a detergentproduct which has remarkably superior resistance to gumming or gelling.

Example 3 A number of detergent compositions, each comprising 45 partsby weight sodium tripolyphosphate, 32 parts by weight of a 41% aqueoussolution of sodium silicate having an average SiO2/Na20 ratio of 2.9,and 20 parts by weight of chlorinated trisodium phosphate, were preparedaccording to the following general processes. In all cases, subsequentto the addition of the last product constituent, the products were agedfor about 15 minutes during which time they were intermittentlyagitated, and the resultant agglomerates were reduced in size to pass a-mesh Tyler screen.

Sample A.-The sodium silicate, in the form of a 41% aqueous solution,was added to a mechanical mixture of the sodium tripolyphosphate andchlorinated trisodium phosphate.

Sample B.-The sodium silicate, in the form of a 41% aqueous solution,was added to the sodium tripolyphosphate prior to the addition theretoof the chlorinated trisodium phosphate.

Sample C.-90% of the total aqueous sodium silicate solution to be usedwas added to the tripolyphosphate prior to the addition thereto of thechlorinated trisodium phosphate. The remaining 10% of the silicatesolution was added subsequent to the chlorinated trisodium phosphateaddition. r

Sample D.-70% of the total aqueous sodium silicate solution was addedprior to the chlorinated trisodium phosphate addition and the remaining30% Was added subsequent to the chlorinated trisodium phosphateaddition.

Each of the samples Vwas evaluated for gumming and gellingcharacteristics by means of the double cup dish- Washer test` describedabove, with the results indicated in the table below. All figures shownrepresent the 300 parts of substantially anhydrous sodiumtripolyphosphate and 114 parts of sodium silicate having an averageSiOz/NazO ratio of about 2.6 were placed in a paddle-type mixer andthoroughly mixed. 88 parts of water were then added to thephosphate-silicate mixture. To the resultant mixture, 133 parts ofchlorinated trisodium phosphate and 20 parts of Pluronic L62 (a con.-qdensate of ethylene oxide with a hydrophobic base formed by condensingpropylene oxide with propylene glycol, the composition having amolecular weight of 2500) were added and thoroughly mixed. The resultantmixture was allowed to age with intermittent agitation. The agglomeratesformed during the foregoing process were reduced to the desired size`'The product was evaluated for gumrning and gelling characteristics bymeans of the double cup dishwasher test described hereinbefore with theresults indicated below:

These values, representing the proportionate amount of detergentcontained in the second detergent cup, may be compared with the valuesobtained in the previous examples wherein the chlorinated trisodiumphosphate was added before the silicate addition.

Having thus described our invention, We claim:

l. A process for preparing detergent compositions comprising awater-soluble alkaline condensed phosphate, a water-soluble alkali metalsilicate, and chlorinated trisodium phosphate which comprises adding toa substantially anhydrous alkaline condensed phosphate an alkalimetalsilicate having a SiOz/alka'li metal oxide ratio in the range from about2.0 -to about 3.4, and `water in an amount at least adequate to wet thesaid condensed phosphate suiiiciently to induce agglomeration andinsuicient to destroy the discrete particle characteristic of thecondensed phosphate-silicate mixture, agitating the mixture whilekeeping the temperature from using above about F., then addingchlorinated trisodium phosphate to the said mixture, agitating theresultant mixture, aging the said resultant mixture to substantiallycomplete hydration while intermittently agitating it and reducing theagglomerates formed to the desired size, the total amount of wateradded, exclusive of water introduced with the chlorinated trisodiumphosphate, being from about 12% to about 25% by weight of the finaldetergent composition, whereby a composition characterized by resistanceto caking on storage and formation of difficultly soluble gels duringuse is produced.

2. The process of claim 1, wherein the water and silicate are added inthe form of an aqueous silicate solution.

3. 'Ihe process of claim 2, wherein the water-soluble ,.7 Y alkali'metalsilicate is sodium ,silicatehayingjan average SiO2'/Na20 ratio of fromabout 2'.7-to about 2.19 1 j, i g 4I V@The process` ofY claim 2, whereina' Vn on-ion-v1c TvsyntheticV detergent irs'radded to theanhydrous;alkaline',con

Y densed phosphate simultaneously with the aqueoussilicate Solution.' "l"1V ""Y'; 1*, 'ff f`ljr` The process of claim ,1, .Whereiu-the alkalinecondensed phosphate issodium tripolyphosphate.,-Vfh Y. The process ofclaim 1 whereinvthre total amount of water to be added lis applieddirectly/to the `substantially anhydrous alkaline condensed phosphate. d7. A process VforY preparing detergent jcompositions comprising aWaterfsoluble alkaline condensed phosphate, ,a Water-soluble alkaliYnietal silicate, and chlorinated trisodium phosphate which comprisesadding to a substantially anhydrous alkaline condensed phosphate anaqueous solution Vof an alkali metal silicatehaving an averageSiOz/alkali metalv oxide ratio inthe range from about 2.0 to about 3.4,the amount of said'silicate solution lcomprising at least 50%N of thetotal amount of silicate solution to'be added, the vtotal amount ofmoisture in said aqueous silicate solution being at least adequate towet the fsaid condensed phosphate suiciently. to` induce agglomerationand insufficient todestroy the discrete particle characteristic of theresultant condensed phosphatesilicate mixture, agitating themixture-While keeping'the temperature thereof from rising above about130 F., then adding thereto chlorinated trisodium phosphate, agi'--tating the mixture, then adding the balance of the 'said aqueoussilicate solution While 4agitating'tltie mixture, the total amount ofWater incorporated inthe said mixture by -the addition of aqueoussilicate solution being from about 12% to about 25% by weight ofthefinal deter- '.gent composition, aging the resultant mixture tosubstantially complete hydration while* intermittently agitating it, andthereafter reducing the'agglomeratesiformedlto the desired size, wherebya composition' characterized by resistance to caking onstorage,andrtoformation.of

ous solutionof an valkali-metal Vsilicatehaving Va'nayera'geSiOz/alkali-metal oxide ratioof from aboutl2.0fto about 3.4, .thertotalamount'of moisture in said aqueous silicate solution beingatleast-adequate to Wet the said condensed phosphatelsuciently Vtoinduce agglomeration and insurcient `to destroythe discreteparticlefcharactc'ristic of the resultant condensedphosphate-silicatemxture, agitatng the mixture While keepingthe,'temperaturey thereof :below about 120 F., the total Yamountoffwater added `Abeing from about 12%,lto` about 25% byiweight of' thefinal detergentrcomposition', thereafter adding chlorinated trisodiumphosphate,la`gitating the rmixture whilefcooling to room temperature,aging the "resultant` mixture. toV substantiallycompleterhydration'while intermittently agitating it, and thereafterYreducingV thevagglomerates 4formed to the desired ,size whereb`y acomposition characterized by resistance to Ycaking on storage and toformationV of difticultly soluble gels during' useis produced.

y' YRei'erences Cited in the file this patent vUNITED STATES PATENTS2,034,361 Sutton Mar. 17, 1936 r2,324,302 Hull July 13, 1943 2,473,822 gkRobinson -g -..v June 2 1, 1949 2,524,394 Madorsky f... Oct.13, 19502,689,225 Anderson etal. Sept. 14, 1954 Mills et al. July 5, 1955

1. A PROCESS FOR PREPARING DETERGENT COMPOSITIONS COMPRISING AWATER-SOLUBLE ALKALINE CONDENSED PHOSPHATE A WATER-SOLUBLE ALKALI METALSILICATE, AND CHOIRNATED TRISODIUM PHOSPHATE WHICH COMPRISES ADDING TO ASUBSTANTIALLY ANHYDROUS ALKALINE CONDENSED PHOSPHATE AN ALKALI METALSILICATE HAVING A SIO2/ALKALI METAL OXIDE RATIO IN THE RANGE FROM ABOUT2.0 TO ABOUT 3.4 AND WATER IN AN AMOUNT AT LEAST ADEQUATE TO WET THESIDE CONDENSED PHOSPHATE SUFFICIENTLY TO INDUCE AGGLOMERATION ANDSUFFICIENT TO DESTROY THE DISCRETE PARTICLE CHARATERISTIC OF THECONDENSED PHOSPHATE-SILICATE MIXTURE, AGITATING THE MIXTURE WHILEKEEPING THE TEMPERATURE FROM USING ABOVE ABOUT 130* F., THEN ADDINGCHLORINATED TRISODIUM PHOSPHATE TO THE SAID MIXTURE, AGITATING THERESULTANT MIXTURE, AGING THE SAID RESULTANT MIXTURE TO SUBSTANTIALLYCOMPLETE HYDRATION WHILE INTERMITTENLY AGITATING IT AND REDUCING THEAGGLOMERATES FORMED TO THE DESIRED SIZE THE TOTAL AMOUNT OF WATER ADDED,EXCLUSIVE OF WATER INTRODUCED WITH THE CHLORINATED TRISODIUM PHOSPHATE,BEING FROM ABOUT 12% TO ABOUT 25% BY WEIGHT OF THE FINAL DETERRGENTCOMPOSITION, WHEREBY A COMPOSITION CHARACTERIZED BY RESISTANCE TO CAKINGON STORAGE AND FORMATION OF DIFFICULTY SOLUBLE GELS DURING USE ISPRODUCED.